The docking of space vehicles, such as the space shuttle orbiter, with space stations or with other space vehicles usually imposes the requirement for in-flight transfer of personnel and cargo. Docking structure designs, which have heretofore been used or proposed to meet this requirement, provide for a combined transfer tunnel and docking mechanism which is mounted in the payload bay of the space shuttle orbiter in coaxial relation with the longitudinal axis of the vehicle. Since the mechanism must be sized to allow through passage of personnel and cargo, the associated large diameter and centerline mounting requires considerable support structure and a heavier structure than would normally be desired from a loads and dynamics standpoint. Further, since the combination structure is fixed in the payload bay during the shuttle's space mission, the net usable payload mass and volume capacity of the orbiter is severely restricted.
In the docking of space vehicles, or a space shuttle orbiter with a space station, the two are brought together usually by means of small maneuvering rockets on the space shuttle orbiter in a maneuver which must provide for correct alignment and positioning of the docking vehicle with respect to docking facilities on the space station. For attenuating potentially substantial impact forces, prior docking mechanisms conventionally employ a plurality of shock absorbers arranged at various angles for accommodating misalignment in the vehicle approach. While such arrangements are appropriate for the docking of small space vehicles, since no great weight penalty is involved in providing for structural rigidity and alignment capability, their use in mechanisms for the docking of large vehicles and space structures may be prohibitively heavy.
A space vehicle coupling mechanism disclosed in U.S. Pat. No. 3,753,536 and representative of the prior art, provides for coupling means on each vehicle with a set of three shocking absorbers incorporated in each of the coupling means for reducing the shock of docking. Other docking mechanisms, of the type utilizing male conical probes and female "drogues", and employing shock absorber arrangements for attenuating the shock of docking impact are disclosed in U.S. Pat. Nos. 3,443,773; 3,608,848 and 3,737,117. U.S. Pat. No. 3,391,881 discloses a docking mechanism including shock absorbing devices for connecting and separating vehicles in space and also provides a sealed tunnel between the vehicles through which personnel can travel from one to the other. All of these prior art mechanisms are characterized by axial coupling of the vehicles and typically require relatively heavy docking structures and impact attenuation devices.